Adding a release note

This amends 403d7d8.

Author: kimgr

clang/docs/ReleaseNotes.rst

@@ -61,6 +61,8 @@ Bug Fixes
   size expression. This was fixed and ``::getArraySize()`` will now always
   either return ``None`` or a ``llvm::Optional`` wrapping a valid ``Expr*``.
   This fixes `Issue 53742 <https://github.com/llvm/llvm-project/issues/53742>`_.
+- We now ignore full expressions when traversing cast subexpressions. This
+  fixes `Issue 53044 <https://github.com/llvm/llvm-project/issues/53044>`_.
 
 Improvements to Clang's diagnostics
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